that along with calculating entropy + byte for byte repetition checking + the percentage of how many times each byte character is in said file will go along way i think :)
You seem to assume that your encrypted file is more or less like a stream of random characters and thus any "deviation" from such "randomness" indicates a corruption.

This of course is a false assumption. There is no need nor reason why an encrypted file should be anything like random noise.

Consider the unbreakable encryption of the "one time pad", or in other words, a key with a length not smaller than the message to encrypt the message. Unless you have access to the key, your encrypted file can be anything but it can never be decrypted. There is absolutely no way you can discern a properly encrypted file from a corrupted file, since actually any string of characters can mean anything. It all depends on the content of the key.

If your encryted file shows certain characteristics, the lack of which indicate corruption, then the original encryption by definition was less secure.

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James

My blog: Imperial Deltronics

In reply to Re^5: Calculating corruption by CountZero
in thread Calculating corruption by james28909

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